The invention relates to an optical arrangement and to a laser diode arrangement with the optical arrangement.
The radiation of a semiconductor diode laser (here simplified, as a diode laser) is characterized by a highly diverging beam, in contrast to conventional laser radiation sources with a laser beam which has a diameter of a few millimeters with low beam divergence in the range of a few mrad, while the divergence for a diode laser exceeds 1000 mrad.
Furthermore, it is known that, in diode lasers, the angle of divergence in the plane, perpendicular to the active layer, i.e. in the so-called "fast axis", is greater than in the plane of the active layer, or in the so-called "slow axis".
To be able to fully use the radiation of a diode laser, which has at least one diode laser bar with several emitters which emit laser light, and which follow one another in the first coordinate direction, the use of collimating and focusing optical arrangements is known. These optical arrangements especially comprise a fast axis collimator which is made as microoptics and which is formed by one cylinder lens which lies with its axis in the first coordinate direction. For all emitters of a diode laser bar there is its own through cylindrical lens with a small focal distance in the immediate vicinity of the facet of the diode laser bar, i.e. at a distance of a few hundred microns from the emitters or from this facet.
To generate higher power laser radiation (for example, for materials working, for medical engineering, for pumping of FK lasers, etc.), it is known to use several diode laser bars in a diode laser stack in several stack layers on top of one another. To each diode laser bar of each stack layer its own fast axis collimator is assigned.
Optimum fast axis collimation requires parallel alignment of the individual beams of the emitter of each bar, so that the emitters are imaged on a line as straight as possible after collimation. In general this cannot be accomplished in ideal form due to nonconformities, i.e. deviations of conformity between the diode laser bars and the fast axis collimator. These deviations can be of varied origin, for example, due to production tolerances and/or deformations during installation, etc. These nonconformities lead, for example, to the emitters of the diode laser bar being imaged not on a straight line, but on a curved line (so-called smile effects) or as an elliptical or cushion-like surface. These imaging errors are generally undesirable since they lead, for example, to enlargement of a common focal spot.
It is an object of the invention is to eliminate these defects.